U.S. patent number 5,144,318 [Application Number 07/738,505] was granted by the patent office on 1992-09-01 for apparatus and method for navigating vehicle using gps.
This patent grant is currently assigned to Nissan Motor Company, Limited. Invention is credited to Hisao Kishi.
United States Patent |
5,144,318 |
Kishi |
September 1, 1992 |
Apparatus and method for navigating vehicle using GPS
Abstract
An apparatus and method for navigating a vehicle using GPS
(Global Positioning System) are disclosed in which a plurality of
GPS antennae are installed on a plurality of positions, e.g., front
and rear ends or left and right sides of the vehicle. A direction
sensor for detecting a forward direction of the vehicle is
installed. Also, a satellite arrangement calculating block for
determining satellites from which electromagnetic waves can be
received through the respective antennae on the basis of; orbit
data on the satellites, the mounting arrangement of the GPS
antennae, and the forward direction of the vehicle is included. A
receive satellite selecting block for selecting the satellites
required to calculate position from among the available satellites
from which each GPS antennae can receive electromagnetic waves is
installed, so that the receive satellites is previously determined,
differently from a diversity method, so speedy and accurate
measurement of the present position of the vehicle can be made.
Inventors: |
Kishi; Hisao (Kanagawa,
JP) |
Assignee: |
Nissan Motor Company, Limited
(JP)
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Family
ID: |
11878870 |
Appl.
No.: |
07/738,505 |
Filed: |
August 1, 1991 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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468723 |
Jan 24, 1990 |
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Foreign Application Priority Data
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Jan 26, 1989 [JP] |
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1-15080 |
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Current U.S.
Class: |
342/357.59;
342/357.65 |
Current CPC
Class: |
G01C
21/28 (20130101); G01S 19/36 (20130101); G01S
19/426 (20130101); H01Q 1/32 (20130101); H01Q
21/28 (20130101) |
Current International
Class: |
G01S
1/00 (20060101); G01C 21/28 (20060101); G01S
5/14 (20060101); H01Q 21/00 (20060101); H01Q
1/32 (20060101); H01Q 21/28 (20060101); H04B
007/85 (); G01S 005/02 () |
Field of
Search: |
;342/352,357,356
;318/649 ;343/713 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Lindenmeier et al "Preiswert und reaktionsschnell", Funkschau, 26,
(1986), pp. 42-45. .
Lindenmeier et al, "Leistungsfahigkeit von Mehrantennen-Diversity
for den UKW-Rundfunk im Auto", Rundfunktechnische Mitteilungen, No.
5 (1987) pp. 221-228..
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Primary Examiner: Blum; Theodore M.
Attorney, Agent or Firm: Lowe, Price, LeBlanc &
Becker
Parent Case Text
CROSS REFERENCE
This is a continuation-in-part application of a U.S. patent
application Ser. No. 468,723 filed on Jan. 24, 1990, now abandoned.
Claims
What is claimed is:
1. A GPS navigating apparatus for a movable object, comprising:
a) a plurality of GPS antennae installed at positions other than
the roof top of the movable object in which the GPS navigating
apparatus is mounted;
b) first means for deriving a forward direction of the movable
object;
c) second means for selecting any of a plurality of satellites from
which each GPS antenna can receive electromagnetic waves on the
basis of orbit data of the respective satellites, mounting
positions of the GPS antennae, and forward direction of the movable
object; and
d) third means for selecting any of the satellites required to
calculate a present position of the movable object from among the
satellites from which the GPS antennae can receive the
electromagnetic waves.
2. A GPS navigating apparatus as set forth in claim 1, which
further comprises fourth means for calculating a present position
of the movable object on the basis of electromagnetic waves
received by the GPS antennae from the number of satellites selected
by said third means.
3. A vehicular GPS navigating apparatus comprising:
a) a plurality of GPS antennae installed at positions other than a
roof top of the movable object in which the GPS navigating
apparatus is mounted;
b) first means for deriving a forward direction of the movable
object;
c) second means for selecting any of a plurality of satellites from
which each GPS antenna enables reception of electromagnetic waves
on the basis of orbit data of the respective satellites, mounting
positions of the GPS antennae, and forward direction of the movable
object; and
d) third means for selecting any of the satellites required to
calculate a present position of the movable object from among the
satellites from which the GPS antennae enable reception of the
electromagnetic waves.
4. A vehicular GPS navigating apparatus as set forth in claim 3,
which further comprises fourth means for deriving any of the
satellites selected by the third means from which said
electromagnetic waves cannot be received by said GPS antennae and
fifth means for determining whether there is at least one of the
satellites from which the corresponding electromagnetic waves
cannot be received by one of said GPS antennae.
5. A vehicular GPS navigating apparatus as set forth in claim 4,
which further comprises fourth means for deriving any of the
satellites selected by the third means from which said
electromagnetic waves cannot be received by the GPS antennae and
fifth means for determining whether there is at least one of the
satellites from which the corresponding electromagnetic waves
cannot be received by said one GPS antenna.
6. A vehicular GPS navigating apparatus as set forth in claim 5,
which further includes eighth means for selecting and receiving
electromagnetic waves derived from a satellite through another GPS
antenna when electromagnetic waves cannot be received by said one
GPS antenna.
7. A vehicular GPS navigating apparatus as set forth in claim 4,
which further comprises ninth means for selecting and receiving a
best PDOP satellite through the one GPS antenna when the fifth
means determines that there is no satellite from which
electromagnetic waves cannot be received by said one GPS antenna
and tenth means for selecting and receving the electromagnetic
waves from a second best PDOP satellite through another GPS
antenna.
8. A vehicular GPS navigating apparatus as set forth in claim 7,
wherein the GPS antennae are installed on both left and right sides
of a trunk lid of a vehicle.
9. A vehicular GPS navigating apparatus as set forh in claim 7,
wherein GPS antennae are incorporated into a front windshield and
rear windshield of the vehicle.
10. A vehicular GPS navigating apparatus as set forth in claim 7,
wherein the GPS antennae are installed on upper surfaces of an
instrument panel and on a rear parcel shelf of a vehicle.
11. A vehicular GPS navigating apparatus as set forth in claim 7,
wherein the GPS antennae are installed on center positions of the
engine bonnet and trunk lid of a vehicle.
12. A vehicular GPS navigating apparatus as set forth in claim 3,
wherein the first means includes a geomagnetic direction sensor
which detects geomagnetism and derives the forward direction of the
vehicle on the basis of detected geomagnetism.
13. A vehicular GPS navigating apparatus as set forth in claim 12,
wherein the first means includes an optical gyroscope for deriving
a turning angular speed of the vehicle and for detecting relative
change in the forward direction of the vehicle.
14. A method of navigating a vehicle using GPS (Global Positioning
System), comprising the steps of:
a) providing a plurality of GPS antennae installed at positions
other than the roof top of the movable object in which the GPS
navigating apparatus is mounted;
b) deriving a forward direction of the vehicle;
c) selecting any of a plurality of GPS satellites from which each
GPS antenna can receive electromagnetic waves on the basis of orbit
data of the respective satellites, mounting positions of the GPS
antennae, and forward direction of the vehicle; and
d) selecting the satellites required to calculate a present
position of the vehicle from among the satellites from which the
GPS antennae can receive electromagnetic waves.
15. A method of navigating the vehicle using GPS as set forth in
claim 14, which further comprises the step of calculating a present
position of the vehicle on the basis of the electromagnetic waves
received by the GPS antennae from the selected number of satellites
in the step d).
Description
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates generally to an apparatus and method
for navigating a vehicle using GPS.
(2) Description of the Background Art
Recently, various types of route guiding systems for vehicles have
been proposed with which to correct accumulated movement errors
relative to a starting point using a gyroscope, a GPS (Global
Positioning System) is utilized.
One of various types of GPS navigation systems has been proposed in
which a single GPS antenna is installed on a roof top of a vehicle
body and the present position of the vehicle is calculated on the
basis of electromagnetic waves derived from a plurality of
satellites by the GPS antenna.
For accurate GPS positioning three satellites are required for two
dimensional positional calculation and four are needed for
three-dimensional positional calculation. The reason that the
antenna is installed to pick up electromagnetic waves as far away
as possible with a wide field of view.
In addition, a plurality of GPS antennae may be installed on
different positions of the vehicle and a diversity method adopted
in which the present position of the vehicle is calculated on the
basis of electromagnetic input from the antennae having the highest
reception sensitivity.
However, since, in the system described above, the GPS antennae are
installed on the roof top of the vehicle, major modification to the
vehicle body is required in order to counter water leakage and
provide a sufficiently rigid roof structure. Consequently, a
specialized vehicle body structure is required and the cost of
implementing the GPS navigating system becomes high.
Additionally, in the diversity method described above, antennae
having high reception sensitivities are used, and measurement of
position on the basis of actual reception results is carried out.
In many cases, a long time may be required to receive
electromagnetic waves from the satellites and calculate the present
position of the vehicle and a great number of opportunities for
measuring position may not occur due to an insufficient number of
satellites. Therefore, lack of practicability becomes a
drawback.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a vehicular GPS
navigating apparatus and method for vehicles, using a plurality of
GPS antennae installed on a preferable position other than the
vehicular roof top and which can accurately and speedily measure
the position of the vehicle.
The above-described object can be achieved by providing a GPS
(Global Positioning System) navigating apparatus for a vehicle
object, comprising: a) a plurality of GPS antennae installed at
positions other than the roof top of the movable object in which
the GPS navigating apparatus is mounted; b) first means for
deriving a forward direction of the movable object; c) second means
for selecting any of a plurality of satellites from which each GPS
antenna can receive electromagnetic waves on the basis of orbit
data of the respective satellites, mounting positions of the GPS
antennae, and forward direction of the movable object; and d) third
means for selecting any of the satellites required to calculate a
present position of the movable object from among the satellites
from which the GPS antennae can receive the electromagnetic
waves.
The above-described object can also be achieved by providing a
vehicular GPS navigating apparatus comprising: a) a plurality of
GPS antennae installed at positions other than the roof top of the
movable object in which the GPS navigating apparatus is mounted: b)
first means for deriving a forward direction of the movable object;
c) second means for selecting any of a plurality of satellites from
which each GPS antenna can receive electromagnetic waves on the
basis of orbit data of the respective satellites, mounting
positions of the GPS antennae, and forward direction of the movable
object; and d) third means for selecting any of the satellites
required to calculate a present position of the movable object from
among the satellites from which the GPS antennae can receive the
electromagnetic waves.
The above-described object can also be achieved by providing a
method of navigating a vehicle using GPS (Global Positioning
System), comprising the steps of: a) providing a plurality of GPS
antennae installed at positions other than the roof top of the
movable object in which the GPS navigating apparatus is mounted; b)
deriving a forward direction of the vehicle; c) selecting any of a
plurality of satellites from which each GPS antenna can receive
electromagnetic waves on the basis of orbit data of the respective
satellites, mounting positions of the GPS antennae, and forward
direction of the vehicle; and d) selecting the satellites required
to calculate a present position of the vehicle from among the
satellites from which the GPS antennae can receive electromagnetic
waves.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a circuit block diagram of a GPS navigating apparatus
applicable to a vehicle in a preferred embodiment according to the
present invention.
FIGS. 2 through 5 are plan views showing an example of a mounted
pair of GPS antennae on a vehicle.
FIG. 6 is an operational flowchart for explaining operation of the
GPS navigating apparatus shown in FIG. 1.
FIGS. 7 and 8 are explanatory views of possible receive areas and
receive not possible areas for the GPS antennae, relative to sky
coordinates.
FIGS. 9 and 10 are explanatory views of the possible areas for the
GPS antennae shown in FIGS. 3 through 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference will, hereinafter, be made to the drawings in order to
facilitate a better understanding of the present invention.
FIG. 1 shows a circuit block diagram of a GPS (Global Positioning
System) navigating apparatus in a preferred embodiment according to
the present invention.
The GPS navigating apparatus in the preferred embodiment includes
two channels CH1 and CH2. Electromagnetic waves from a plurality of
GPS satellites trapped by the respective channels are used to
measure the position of the GPS apparatus, i.e., an absolute
position of the vehicle in which the GPS navigating apparatus is
mounted.
In FIG. 1, 1A denotes a first GPS antenna installed on a part of a
vehicle body except a roof top portion of the vehicle body as will
be described later and 1B denotes a second GPS antenna installed on
another portion of the vehicle body as will be described later.
FIGS. 2 through 5 show positioning examples for the first and
second GPS antennae 1A and 1B.
In FIG. 2, the first and second GPS antennae are installed on both
sides of a trunk lid of the vehicle body C. In FIG. 3, the first
and second GPS antennae 1A, 1B are installed respectively on inner
sides of a front windshield and rear windshield of the vehicle body
C. In FIG. 4, the first and second GPS antennae are installed on
upper surfaces of an instrument panel and rear parcel shelf of the
vehicle body C.
In FIG. 5, the antennae 1A, 1B are installed on a bonnet and trunk
lid of the vehicle body C.
Referring again to FIG. 1, each channel CH1 and CH2 includes a
frequency converter 2 having a reference quartz oscillator 21,
multiplier 22, amplifier 23, and a mixer 24 included in the
frequency converter 2. The frequency converter 2 serves to convert
the received signal from the first or second antenna 1A or 1B into
a frequency converted signal with reference to a multiplied signal
of the multiplier 22 (the reference quartz oscillator 21 generates
a reference frequency signal which is to be multiplied by the
multiplier 22).
Furthermore, each channel CH1 and CH2 includes a pseudo distance
measuring circuit 3 having a collator 31, PN (Pseudo Noise) code
generator 32, code phase setting switcher 33, and pseudo distance
measuring instrument 34. The pseudo distance measuring circuit 3
takes a correlation between a PN code of the frequency converted
signal derived from the frequency converter 2 and internally
generated PN code and carries out a PN demodulation.
Furthermore, each channel CH1 and CH2 includes an orbit data
demodulator 4 having a band-pass filter 41, phase demodulator 42,
carrier NCO 43, and carrier frequency setting switcher 44. A
correlated output signal from the pseudo distance measuring circuit
3 is input into the phase demodulator 42 via the band pass filter
41 to derive a phase of the received signal from the corresponding
antenna 1A or 1B and a phase difference. It is noted that the orbit
data modulator 4 further includes a carrier frequency code phase
calculator 45.
Each channel CH1 and CH2 includes a reception control calculator 5
which transmits the PN code phase and a carrier frequency data to
the PN code generator 32 within the pseudo distance measuring
circuit 3 and to the carrier NCO within the orbit data demodulator
4.
Each channel CH1 and CH2 includes a position measurement and
calculating block 6 having a microcomputer, deriving the position
of the vehicle according to the result of measurement of the pseudo
distance and deriving velocity and direction of each satellite
according to Doppler frequency shift of the received signals of the
respective antennae.
Numeral 7 denotes a display controller for displaying the position
of the vehicle derived by the position measurement and calculation
block together with a map. Numeral 8 denotes a map memory for
storing a data on the map and having a CD-ROM (Compact Disc Read
Only Memory) and CD-ROM controller. Numeral 9 denotes a display of
CRT.
Numeral 10 denotes a directional sensor including a geomagnetic
sensor for detecting a geomagnetism and deriving a forward
direction of the vehicle and a gyroscope (an optical gyroscope
using a optical fiber) for detecting a relative change in the
forward direction of the vehicle. Since the vehicle forward
direction is determined according to the detection signal of the
directional sensor 10, the directional sensor 10 includes a
direction calculating circuit.
It is noted that the position measurement and calculation block
serves to derive one of the satellites which is receivable from one
of the antennae 1A and 1B on the basis of the derived position of
the vehicle and orbit data on the GPS satellites and serves to
select one of the satellites whose electromagnetic wave is to be
received via one of the antennae 1A or 1B according to the derived
arrangement of the satellites on their orbits. Then, the position
measurement and calculation block 6 serves to select the satellites
to be received from the respective antennae 1A and 1B.
It is noted that the structures and functions of the frequency
converter 2, pseudo distance measuring circuit 3, orbit data
demodulator 4, and reception control calculator 5 are exemplified
by a Japanese Patent Application First Publication Showa 61-198072
published on Sep. 2, 1986, the disclosure of which is herein
incorporated by reference.
Each GPS satellite (not shown) transmits a navigating signal on
electromagnetic waves having two frequencies in order to correct
errors generated when passing through an ionosphere. In this case,
the navigating signal is usually subjected to a diffusion spectrum
modulation by means of a pseudo noise signal (PN signal). Such a
navigating signal is trapped by means of one or both of the GPS
antennae 1A or 1B and transmitted to the frequency converter 2. The
reference quartz oscillator 21 supplies a predetermined frequency
signal to the multiplier 22 in which a local oscillation signal is
obtained from a signal supplied from the reference quartz
oscillator 21. The multiplier 22 supplies the local oscillation
signal to the frequency converter (mixer 24). The received signal
of the frequency converter 24 is frequency converted on the basis
of the output signal of the multiplier 22. Then, the amplified
signal of the amplifier 23 is supplied to the collator 31. The
output of the PN code generator 28 generating the same code as the
PN code of one of the satellites received by means of the code
phase setting switcher 33 is supplied to the collator 31. The
collator 31 takes the correlation between the output signal of the
PN code generator 32 and the PN code of the amplified signal from
the amplifier 23. That is to say, the received signal under the
spectrum diffusion is subjected to a reverse diffusion with the
output signal of the PN code generator 32 and subjected to the PN
demodulation. The output signal of the collator 31 is introduced
and filtered into the band pass filter 41. The output signal is
introduced into the phase demodulator 42. The phase demodulator 42
detects the phase difference between the frequency signal supplied
from the carrier NCO 43 under a switch setting action of the
carrier frequency setting switcher 44, i.e., the same frequency as
the received signal of the corresponding antenna 1A or 1B. The
phase difference is introduced into the reception control
calculator 5. The reception control calculator 5 outputs it output
signal to the code phase setting switcher 33 and carrier frequency
setting switcher 44. The PN code phase and carrier frequency data
are supplied to the PN code generator 32 and carrier NCO 43
respectively in response to the output signal from the reception
control calculator 5. The collator 31, band pass filter 41, phase
demodulator 42,, reception control calculator 5, code phase setting
switcher 33, and PN code generator are integrally formed in a phase
synchronization loop. On the other hand, the phase demodulator 42,
reception control calculator 5, carrier frequency setting switcher
44, and carrier NCO 43 are integrally formed in a phase
synchronization loop.
It is noted that in a case where the output signal of the phase
demodulator 42 is introduced into the reception control calculator
5 and the reception control calculator 5 cannot detect the phase
difference between the received frequency from the phase
demodulator 42 and the frequency of the carrier NCO 43, the
reception control calculator 5 and position measurement and
calculation block 6 determine that it is impossible to measure the
position of the vehicle. At this time, the position
measurement/calculation block 6 refers to the output signal of the
positional sensor 10.
As described above, the PN code generator 32 supplies the signal
for PN demodulation to the collator 31. On the other hand, the code
signal is supplied to the pseudo distance measuring instrument 34.
The pseudo distance measuring instrument 34 can measure a pseudo
distance to the one GPS satellite according to a phase value of the
PN code generator 32 on the basis of the clock frequency generated
from the reference quartz oscillator 21 and signal of the PN code.
The measured pseudo distance is introduced into the position
measurement/calculation block 6.
On the other hand, the output line of the phase demodulator 42 is
branched into the input terminal of the position
measurement/calculation block 6. The operation of the position
measurement/calculation block 6 and carrier frequency code phase
calculator 45 will be described later. The display controller 7
receives the output signal of the position measurement/calculation
block 6 so that the position and forward direction of the vehicle
are displayed on a map from the map memory 8 through the display
unit 9.
It is also noted that the circuit construction of the GPS
navigating apparatus is also exemplified by European Patent
Application Publication No. 0 166 300 A3 published on Jan. 2, 1986
and U.S. Pat. No. 4,445,118 issued on Apr. 24, 1984, the disclosure
of which is also herein incorporated by reference.
An operation of the position measurement and calculation block 6 of
the GPS navigating apparatus will be described with reference to
FIG. 6.
A progran shown in FIG. 6 is started upon turning on of a power
supply of the GPS navigating apparatus.
In a step 609, a CPU of the microcomputer in the position
measurement/calculation block 6 selects an optimum satellite to be
used to derive the present vehicle position by selecting the
satellite which provides, e.g., a mininum value of PDOP (Pseudo
Dilution Of Precision).
In a step 610, the CPU calculates the forward direction of the
vehicle on the basis of a signal from the geomagnetic sensor or
gyroscope.
In a step 611, the CPU calculates the satellites from which
electromagnetic waves cannot be received considering the shape of
the vehicle and installed position of the two antennae 1A and
1B.
That is to say, GPS electromagnetic waves have strong linearity at
about 1.5 GHz and cannot be received should the antenna be
positioned in a shadow of the vehicle roof, for example. In the
first preferred embodiment, the vehicle shape, structure, and
appearance are not changed. Since the antennae 1A and 1B are
installed on the vehicle body as shown in FIGS. 2 through 5.
positional situations arise in which electromagnetic waves from a
particular satellite (or satellites), cannot be received.
For example, as shown in FIG. 2, in a case wherein both antennae 1A
and 1B are installed on both sides of the right and left sides of
the trunk lid, satellite positions from which electromagnetic waves
cannot be received are shown as NG in FIGS. 7 and 8.
That is to say, in FIGS. 7 and 8, suppose that R denotes the
direction of the right side of the vehicle, L denotes the direction
of the left side of the vehicle, F denotes the direction of the
left side of the vehicle, F denotes the direction of the front of
the vehicle and B denotes the direction of the rear of the
vehicle.
From a sky area of the satellites viewable from the first and
second antennae 1A and 1B, the CPU derives an oblique portion are a
NG from which electromagnetic waves cannot be received and an area
OK from which electromagnetic waves can be received.
In a step 611, the CPU derives which satellites from which
electromagnetic waves cannot be received from the present
arrangement of the satellites or orbits.
Various positioning examples are shown, FIG. 3 in which both GPS
antennae 1A and 1B are incorporated in the front windshield and
rear windshield, of FIG. 4 in which both GPS antennae 1A and 1B are
arranged on the upper surface of the instrument panel and rear
parcel shelf, and of FIG. 5 in which both GPS antennae are arranged
on a bonnet and trunk lid center portion. In the embodiment of FIG.
5, the electromagnetic wave receivable OK area and the
electromagnetic wave receive not possible NG area are roughly shown
in FIGS. 9 and 10.
In a step 612, the CPU determines whether there is a satellite from
which electromagnetic waves cannot be received by the channel CH1.
If not (NO) in the step 612, the routine goes to a seap 615. If it
is present (Yes) in the step 612, the routine goes to a step
613.
In the step 613, the CPU excludes satellites from which receipt of
electromagnetic waves becomes impossible from among the satellites
selected at the step 609 and selects and receive the satellite
which has the best PDOP from among the receivable satellites.
In a step 614, satellite from which electromagnetic waves cannot be
received on channel CH1 is selected to be received on channel
CH2.
On the other hand, in step 615, the satellite which the best PDOP
is selected and received on channel CH2 to assist channel CH1.
In the preferred embodiment, since the channel CH1 concerned with
the antenna 1A is a main receiver with electromagnetic waves of the
satellites which belong to the CH1 reception impossible area NG
being received by the channel CH2 2, in all receivable states the
channel CH2 is auxiliary used. No problems in selecting the receive
satellite, as in a diversity method, occurs and speedy calculation
of the present position of the vehicle can be achieved.
Furthermore, since the pair of GPS antennae 1A and 1B are compactly
installed on front and rear ends or left and right side of the
vehicle body in a form so as not to disturb vehicle operation, as
shown in FIGS. 2 through 5, the GPS antennae do not worsen the
design of the vehicle body and do not affect drivin safety.
Therefore, according to the present invention, cost-reduced and
general purpose vehicles employing GPS navigating can be
achieved.
It will fully be appreciated by those skilled in the ar that the
foregoing description has been made in terms of the preferred
embodiments and various changes and modifications may be made
without departing from the scope of the present invention which is
to be defined by the appended claims.
* * * * *